Gases such as arsine, phosphine, silane, diborane, dichlorosilane, hydrogen chloride, chlorine, etc. are used for the production of semiconductor materials, but, when diffused in the air, these gases are very hazardous in view of their toxicity, ignitability and corrosiveness.
Opening or closing of cylinders containing such gases are carried out by hand, for example, in the replacement thereof. However, there is a fear that the operators may be exposed to them in unexpected accidents such as failure of the caps.
In case of some accidents at places where the aforesaid gases are used or on piping terminating thereat, an emergency shut-off valve is usually mounted in the piping from the gas cylinder to those places to shut off the supply of such gases. However, when a piping trouble arises upstream of the emergency valve, the gases continue to flow out so that the valve of the cylinder should be closed to positively shut off the supply of the gases. Furthermore, even after that trouble is removed, it is advantageous in view of safety that the gases are connected by opening the valve of the cylinder in a remote-controlled manner.
As disclosed in Japanese Tokkaisho Nos. 54-83120 and 57-48358, for instance, the known remote-control apparatus for closing the valve of a high-pressure gas cylinder includes a spindle-rotating member fitted onto a valve spindle, which is designed to be closed by a rachet spanner driven by a compressed gas.
However, this remote-controlled valve closing apparatus is only intended to close the valve of a cylinder, and is used with a chlorine gas cylinder used for the sterilization of service water. This type apparatus is only used and applied to the arrangement wherein the spindle projects above the valve wheel, and is thus inconvenient in that the spindle-rotating member should be removed prior to replacement of the cylinder.